The properties of polyesteramides based on PET and nylon 2,T (PETA) using DMT, the bis(esterdiamide) T2T-dimethyl (N,N'-bis(p-carbo-methoxybenzoyl)ethanediamine) and 1,2-ethanediol as starting materials has been studied. A PETA series with an increasing T2T content (0.1-30 mol%) has been synthesised and studied. It was observed by dynamic mechanical analysis, that the T-g, flow temperature (T-fl) and modulus of the rubbery plateau of PETA increased with increasing T2T content, implying a considerable improvement in the dimensional stability. The increase in T-g was approximately linear with T2T content. The T-m and T-fl were also increased with increasing diamide content. The increase in T-fl was non-linear, indicating that random co-crystallisation of the eater and amide segments did not occur. The amide segments are expected to self-assemble in the melt, and preferentially order with other amide segments. The crystallisation rate of PET was considerably improved by the incorporation of a small amount of T2T (0.1 mol%). By using higher concentrations of T2T, the crystallisation rate of PETA was improved even further. The crystallisation of PETA from the melt was studied using time-resolved WAXD measurements. It was observed that for PETA(25), crystalline amide segments were present at 310 degrees C, this being well above the T-m measured by DSC (280 degrees C). The hypothesis is that at high amide concentrations, small alternating segments are formed (amide-ester-amide), these have a much higher melting temperature and are present in their crystalline form above the melting temperature of the polymer. Upon cooling, these segments form the nucleation sites for PETA.